Turn-table.



G. N. CRAWFORD.

TURN TABLE.

APPLICATION FILED mu 6, 1909.

1,031,425. I Patented July 2, 1912.

3 SHEETS-SHEET l.

fi W L IN VE/V TOR Wild/E8858: a g

G. N. CRAWFORD.

. TURN TABLE.

APPLIOATION FILED MAY 6, 1900.

1,031,425. Patented July 2,1912.

3 SHEETS-SHEET 2.

WlT/VE88E8 INVENTOR "ORA/5Y5 G. N. CRAWFORD.

TURN TABLE.

APPLICATION FILED MAYG, 1909.

1,03 1 ,425, k Patented July 2, 1912.

3 SHEETS-SHEET 8.

yly% @24 WITNE88E8: I v INVENTOR Arm/mm I "Be it known that I, Gnonon I I UNITED STAWEN OFFICE.

GEORGE N. CRAWFORD, OF CHICAGO, ILLINOIS, LBSIGNOB T0 LIDGERWOOD MANU- FACTURING COMPANY, OF NEW YORK, N. Y., A. CORPORATION OF NEW YORK.

- TURN-TABLE.

Specification of Letters Patent.

Application filed Kay 8, 1909. Serial No. 494,482.

Patented July 2, 1912.

To all whom-it may concern.

N. Cnawronn, a citizen of-the United States, and a resident ofGhicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Turn-Tables, of which the following is a specification.

The use of turn-tables is common in connection with many types of machines bearing derricks and the like which it is desired to operate atdiiferent points around the machine, the base of the machine remaining in a fixed position and only the upper portion or that bearing the derrick, etc., being adapted to turn. Moreover, such a use of turn-table is very commonly made in connectionwith machines adapted to operate and movable on a track, it being desired to operate the derrick or the like carried by the-machine from any desired point on either side or end and the engine, boiler, etc., for generating the. power to operate the machine generally being carried -on the turn-table.-

required, the construction being such as to avoid friction between moving parts and obviate any danger of difliculty in turning the table through jamming or the like.

Furthermore, I have provided a novel construction and arrangement of mechanism for turning the table.

In .the drawings herewlth I have shown and will hereafter describe my invention as embodied in the turn-table of an excavating machine adapted to operate upon a trac but it will be obvious that various and desired uses of my invention may be made without departing from the spirit of the i invention which consists in the design, ar-

rangement, combination and operation of parts as set forth inand falling within the scope of the claims hereto ap ended.

In the drawings herewith like characters of reference denote like parts in all the figures thereof; Fi re 1 represents a side view in elevation o im excavating machine provided with a turntable embodying my invention; Fi 2 represents a plan view of a turn-tab e embodying my invention, the top section or floor portion of the turntable bearing the floor of the excavating machine being removed; Fig. 3 represents view in elevation taken centrally across a turntable embodying my invention.

In the excavating machine shown for the purpose of illustration, the engine A boiler B and derrick C are carried on the floor portion D of the turntable. To the floor portion D underneath the same is secured a rail circle 1 resting upon wheels 2 prefer ably tapered, which in turn rest upon a rail circle 3 mounted on the stationary base4, which latter is provided in this instance with wheels 6 resting upon a track 7. In the portion D of the turntable centrally of the rail circle 1 is mounted a casting 8 ex tending downward and entering a casting 9 carried by the base 4 and positioned centrally of the rail circle 3 on said base. The casting 9 is provided with v a circular shoulder 10 upon which rests a circular plate 11; from the plate 11 radiate the arms 12 of a s ider, each arm having mounted thereon ad acent its end a tapered wheel 2 and the ends of the arms 12 beingunited by a restraining ring 13. From the above description it will be seen that the rail circle 1 secured underneath the floor portion of the turntable, rests and is free to turn upon the wheels 2, while the wheels 2 carried by the spider rest and are free to move on the rail circle3 on the base of the turntable. The turning of the floor portion of the turntable about the axis of its rail circle 1 1s inde endent of any turning of the spider bearing wheels 2 about its axis and vice versa; in this manner the friction between moving parts upon the rotation of the turntable is reduced to a minimum. In the preferred form of construction the turning power is applied directly to the floor portion of the turntable'which then rotates or turns on 'wheels 2, the latter moving on the rail circle on the base, the turning of the wheel spider bein at a slower rate of speed than t at of the oor portion. The turn-table so constructed may be readily and rapidly set in motion with little power and its movement easily controlled or checked.

For the purpose of securing the rotation--- for vertical shafts 19 extending through the same. Each shaft 19 is provided at its lower end with a gear pinion 20, the pinions 20 being in a horizontal plane with rack 14. An endless chain 21 passes around the pinions 20, its inner length meshing on its outer portion with the teeth of rack 14 and being pressed outward to conform to the curve of the rack sufiiciently to secure an engagement between the chain and a plurality of the teeth of the rack. Shaft 19 passing through bearing 17 extends above the bearing'and is provided at its top with a bevel gear 22 en.

gaging with a pinion 23 on shaft 24, which is driven from an engine on the turntable. In orderto maintain a tension on the chain 21 to; keep the same stretched tightly between the pinions 20, and in secure engagement with the rack, casting 18 passes through an enlarged a erture in the under flooring of the turn-ta le and is provided with a plate 25 resting against the under side of the upper flooring of the table and a second plate 25 resting on the under flooring around the aperture or opening therein. Thus,'casting 18 is capable of movement laterally away from or toward casting 17,

and a tension spring 26 is provided secured to the turn-tab e and to casting 18 which tends to pull the latter away from the casting 17 and thus maintains a tension on the chain 21 to keep the same stretched tightly between the pinions 20. 'Movement of the turn-table is readily secured by the operation of shaft 24 to move the chain 21, the direction of rotation of the turn-table being in a direction opposite to the movement of the chain at its chain 21 is always stretched tightly between the pinions around which it passes and is held in firm engagement with the rack, at

the same time be ng capable of yielding to any unusual strain or shock without breaking.

A turn-table embodying my invention is particularly efiicient becauseof the ease and simplicity with which it may be turned and its movement controlled.

Having thus described my invention, what I claim as new and desire to secure by Let- 'tersPatentis as follows 1. A turn-table comprising a stationary point of engagement with rack-14. The

base, a floor portion and means for. turning the floor portion, said means comprising a circular toothed rack fixedly mounted on the base, an endless chain carried by the floor portion and meshing with the outer face of one of its runs with said rack, and means on the turn table for operating the chain.

2. A turn-table comprising a stationary base, a floor portion and means for turning the floor portion, said means comprising a circular toothed rack fixedly mounted on the base, two vertical shafts extending downward from the floor portion, a pinion at the lower end of each shaft, an endless chain passing around said pinions and meshing at the outer face of one of its runs with the rack, and means on the turn table for operating one of said shafts.

3. A turn-table comprising a stationary base, a floor portion, and means for turning the floor portion, said means comprising a circular toothed rack fixedly mounted on the base, a stationary pinion and a movable pinion. mounted on the floor portion and movable therewith, an endless chain passing around said pinions and meshing at the outer face of one of its runs with said rack,

a tension member connected to said movable pinion and means on the turn table for operating one of said pinions.

4. A turn-table comprising a floor portion, hoisting apparatus thereon, a base mounted upon running wheels, a hoisting engine mounted upon said floor portion for operating the hoisting apparatus, and including a horizontal power shaft, and means for turning the table comprising a rack on the base, a pair of vertical shafts on the floor portion, a sprocket chain running over sprockets on said shafts and engaging said rack, with the outer face of one of its runs, a horizontally disposed shaft geared to the said power shaft and to one of said vertical shafts whereby the hoisting engine may be operated to drive the turn-table.

5. A turn-table comprising a floor portion, a base upon which said floor portion is r0- tatably mounted, means for driving the floor portion comprising a rack mounted on the base, vertical shafts carrying sprockets supported by the floor portion, one of said shafts being mounted in a cushioned bearing to permit it to move toward the other shaft, a sprocket chain runnin sprocketson said shafts and mes ing at the outer face ofone of its runs with sa1d rack, and means for driving one ofthe shafts. V

6. A turn table comprising a floor portion, a base upon which said floor portion is rotatably mounted, means fordriving the floor portion comprising arack mounted on the baseyvertical' shafts carrying sprockets supported by the floor portion and moving therewith, one of said shafts being slidable toward and away from the other shaft, a.

over the tension device to permit said slidable shaft name to this specification in the presence of to] slide toward the other shaft, a sprocke two subscribing witnesses. c ain running over the s rockets on sai shafts and meshing at the iiuter face of one GEORGE CRAWI 5 of its runs with said rack, and means for Witnesses:

driving the chain. WM. R. ELDEN,

In testimony whereof I have signed my M. Sco'rr. 

